Driver circuit for magnetic core device with temperature compensation means



Jan. 27, 1970 J, H. WHITLEY ETAL 3,492,507

DRIVER CIRCUIT FOR MAGNETIC CORE DEVICE WITH TEMPERATURE COMPENS ATION MEANS Filed July 2, 1964 Tale. 0

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United States Patent 3,492,507 DRIVER CIRCUIT FOR MAGNETIC CORE DEVICE WITH TEMPERATURE COMPENSATION MEANS James Heyward Whitley, Harrisburg, and Lawrence Grebe Wiley, Camp Hill, Pa., assignors to AMP Incorporated,

Harrisburg, Pa.

Filed July 2, 1964, Ser. No. 379,994 Int. Cl. H03k 3/02 US. Cl. 307270 6 Claims ABSTRACT OF THE DISCLOSURE An electronic circuit comprises solid state switch means connected to be sequentially driven to conduction with an input provided for applying a voltage source to the switch means, means in a circuit with each switch means and responsive to conduction thereof to provide output pulses, and means connected to this last-mentioned means to provide temperature compensated control pulses varying in amplitude in accordance with the requirements of the electronic circuit.

This invention relates to a drive circuit for a shift register and the like.

An object of this invention is to provide a drive circuit for operating magnetic core devices, such as, shift registers, over a wide temperature range and at high speeds.

Another object of this invention is to provide a drive circuit which is very reliable, is easy to control and is relatively simply and inexpensive.

A more specific object of the present invention is to provide a drive circuit for energizing at high speed and over a wide temperature range a magnetic core shift register using multi-aperture cores.

In a multi-aperture (MAD) core shift register, such as shown in US. Patent No. 2,995,731, transfer of information from one core in the register to the next is accomplished by driving the one core with a properly shaped advance current which returns the core to clear condition and simultaneously causes the transfer of the information stored in this core to the next core. Thereafter, the latter core is cleared by a second advance current, and so on. Between the advance currents applied to the cores, there is also applied a prime current which, as understood, conditions each given core in the register so that thereafter upon the occurrence of an advance current, information can be transferred to the next core. The construction and operation of such a shift register is explained in detail in the above-mentioned patent.

Now, one of the problems with a shift register of this kind is the difficulty of providing the proper prime current over a wide temperature range with normal variations in source voltage. This problem becomes particularly diflicult when the shift register is placed in an environment where the temperature varies over a wide range for extended periods of time. The present invention provides an improved supply unit particularly suitable for a magnetic core device, which can be operated at high speed, yet it uses only solid state devices and it is extremely reliable in operation over a wide temperature range.

Heretofore, the charging and discharging of a single capacitor through a pulse-forming network provided distinct output pulses to supply prime current and advance current to the windings of a shift register device from a single source of supply. The circuit of this prior approach has proven highly successful in that it is less expensive and more reliable than prior known circuits of the same capability. However, one drawback of this circuit arrangement has been that the permissable voltage source variation for providing prime current over an extended temperature range had to be kept within a very small variation which has resulted in an almost intolerable restriction in voltage source variation, and, if the voltage source varied outside the permissable variation, then improper priming occurred.

In accordance with the present invention, in one specific embodiment thereof, a single capacitor is arranged to be charged from a source of supply through a temperature compensation circuit means. Thereafter, the charge which has accumulated in the capacitor is discharged on command through a four-layer diode switch or the like through an advance winding of the shift register, and after being recharged is then discharged on command through another similar four-layer diode switch or the like through another advance winding of the shift register to provide proper sequencing to the prime and advance circuits. The cores of the register during and between the advance currents are supplied by a continuous temperature compensated prime current which does not interfere with the advance currents and which nonetheless provides the necessary priming current. This cycle of charging and recharging of the capacitor through the temperature compensation circuit to provide the prime and advance currents can be carried out at high speed with a high degree of proper sequence, fail-safe operation and a higher permissible voltage source variation in providing prime current.

Other objects and attainments of the present invention will become apparent to those skilled in the art upon a reading of the following detailed description when taken in conjunction with the drawings in which there is shown and described an illustrative embodiment of the invention; it is to be understood, however, that this embodiment is not intended to be exhaustive nor limiting of the invention but is given for purposes of illustration and principles thereof and the manner of applying it in practical use so that they may modify it in various forms, each as may be best suited to the conditions of a particular use.

In the drawings:

FIGURE 1 is aschematic diagram of the circuit of the invention; and

FIGURE 2 is a graphic representation of permissible and actual prime current.

Turning now to FIGURE 1, a suitable source of voltage is denoted at 10 which, as illustrated, is a battery having its negative terminal connected to ground. The positive terminal of the battery is connected to a parallel R-C network 11 which, in turn, is connected to one side of an inductor 12. The other side of inductor 12 is connected to the anodes of serially connected diodes 13 and 14.

The cathode of diode 13 is connected to one side of resistor 15 while the other side of this resistor is connected to point 16. One side of winding 17, winding 18 and winding 19 of shift register 20 is also connected to point 16. Windings 17, 18 and 19 are, respectively, the ADVANCE O winding, ADVANCE E winding and the prime winding of the shift register.

Capacitor 21, inductor 22 and resistor 23 are serially connected between the other side of prime winding 19 and ground. Resistor 24 and thermistor 25 are connected in series between the cathode of diode 14 and between prime winding 19 and capacitor 21.

The other side of inding 17 is connected in series with a four-layer diode 26 and diode 27 which has its cathode connected to ground. The other side of winding 18 is likewise serially connected to a four-layer diode 28 and diode 29 which also has its cathode connected to ground. Four-layer diodes 26 and 28 act as solid state switches SW; and SW Of course, diodes 26 and 28 may take the form of silicon-controlled rectifiers without departing from the spirit of the invention. A negative TRIG. O and TRIG. E voltage pulse from a conventional trigger circuit (not shown) is applied respectively to capacitors 30 and 31 which, in turn, are respectively connected between diodes 26, 27 and diodes 28, 29.

FIGURE 2 illustrates a range map of permissible pulse prime operating values with the ordinate denoting temperature in degrees eentrigrade and the abscissa indicative of prime current in peak milliamperes. Solid line 32 in dicates the minimum prime current and solid line 33 is indicative of the maximum prime current. Broken line 34 between lines 32 and 33 denotes the actual values of prime current fiowing in the prime circuit when the driver circuit of FIGURE 1 is used.

As can be discerned, prime current increases with a decrease in temperature and decreases with an increase in temperature by means of the temperature compensation circuit means in the priming circuit means; this permits a much wider variation in source voltage and a more desirable driver circuit for use over a Wide temperature range.

The circuit of FIGURE 1 operates in the following manner: Upon application of supply voltage from 10, the capacitor from network 11 and capacitor 21 charge in series through inductors 12 and 22, resistor 23, and the parallel-series circuit of resistor 15, diode 13, thermistor 25, resistor 24 and diode 14. This charge current pulse may be made into a suitable time duration and amplitude to properly prime the magnetic circuit, to which it is connected by proper selection of component values. Upon completion of the charge cycle, the capacitor of network 11 discharges through the resistor thereof.

A portion of the total charge current flows through resistor 15 and diode 13. The remainder of the current flows through thermistor 25, resistor 24, and diode 14. Since the resistance of thermistor varies with temperature, the exact portion of the total charge current which flows through resistor 15, diode 13, and the magnetic circuit varies with temperature. By proper selection of resistors 15, 24 and thermistor 25, the current flowing through the magnetic circuit may be made to vary with temperature as illustrated by dotted curve 34 in FIG- URE 2.

Upon completion of the above charge cycle, if a trigger pulse is applied to capacitor 30, switch SW switches to a conducting state and capacitor 21 discharges through inductor 22, resistor 23, diode 27, switch SW and the magnetic circuitry, thus, producing a proper advance pulse. At the end of this discharge phase, capacitor 21 and the capacitor of network 11 recharge, as described above, thereby producing a proper prime pulse.

A similar action results from the application of a trigger pulse to capacitor 31.

Diodes 13 and 14 prevent the prime circuit from being loaded by thermistor 25, resistor 24 and resistor 15. Diodes 27 and 29 offer a high input impedance to the trigger pulses and a low impedance to advance currents.

While the foregoing temperature compensation circuit means has been described in conjunction with a drive circuit similar to that disclosed in Ser. No. 52,295, filed Aug. 26, 1960, now U.S. Patent No. 3,221,176, and assigned to the present assignee, it can also be used in conjunction with the drive circuits of Ser. No. 114,695, filed June 5, 1961, now U.S. Patent No. 3,154,693; Ser. No. 156,616, filed Dec. 4, 1961, now U.S. Patent No. 3,154,694, and Ser. No. 331,999, filed Dec. 20, 1963, now U.S. Patent No. 3,315,092, each of which is also assigned to the present assignee.

As can. be discerned, there has been disclosed a driver circuit which includes temperature compensation circuit means that is capable of operation over a wide temperature range to provide proper priming current to a shift register means or the like.

It will, therefore, be appreciated that the aforemen tioned and other desirable objects have been achieved; however, it should be emphasized that the particular embodiment of the invention, which is shown and described herein, is intended as merely illustrative and not as restrictive of the invention.

What is claimed is:

1. A magnetic core driver circuit having a priming operation and an advance operation, the priming operation including a current-charging path having a current source, magnetic core priming winding and charging-capacitor means connected in series therewith, the improvement comprising a temperature compensation circuit wherein said current-charging path additionally includes plural resistance means connected in parallel on one side to said current source and on the other side at either end of said core priming winding, and one of said resistance means including means that varies as a function of temperature so that part of the charging current is directed through said core winding and part of the charging current is caused to bypass said core winding.

2. In a pulse generator circuit for supplying short current pulses to alternate inductive winding means of a magnetic shift register and the like, a voltage source to provide a charging current, first and second switch means adapted to be triggered on by said charging current, a first pulse-forming circuit including a blocking diode and a capacitor connecting said first switch means to one of the inductive winding means, a second pulse-forming circuit including another blocking diode and said capacitor connecting said second switch means to another of the inductive winding means, a parallel resistance means connected in series With said voltage source and having legs connected on each side of one of the inductive winding means, and one of said resistance means defining including means that varies as a function of temperature so that part of said charging current is directed through the one of the inductive winding means and part of said charging current is caused to bypass the one of the inductive windmg means.

3. In a pulse generator circuit for supplying short current pulses to a plurality of serially-connected load devices, a voltage source to provide a charging current, first and second switch means adapted to be triggered on by said charging current, a first pulse-forming circuit including a blocking means and a storage means connecting said first switch means to one of the serially-connected load devices, a second pulse-forming circuit including another blocking means and said storage means connecting said second switch means to another of the serially-connected load devices, a parallel resistance means connected in series with said voltage source and having legs connected on each side of one of the serially-connected load devices, and temperature-varying means in one of said legs that varies as a function of temperature so that part of said charging current is directed through the one of the serially-connected load devices and part of said charging current is caused to bypass the one of the serially-connected load devices.

4. In a pulse generator circuit according to claim 3 wherein said blocking means is a diode.

5. In a pulse generator circuit according to claim 3 wherein said storage means is a capacitor.

6. In a pulse generator circuit according to claim 3 wherein said temperature-varying means is a thermistor.

References Cited UNITED STATES PATENTS JOHN S. HEYMAN, Primary Examiner U.S. Cl. X.R 307278, 310 

